THE other night while I was watching television, Zooey Deschanel said “penis,” and I didn’t laugh. I didn’t even chuckle.

“Doesn’t this guy read the papers?” you’re thinking. “Doesn’t he know that everyone is calling this a comeback season for the sitcom and that Ms. Deschanel’s show is one of the most popular around? Dude’s not right in the head.”

I thought so too, for a while. But I came to realize that I’m not the problem. The problem is that we’ve reached the End of Comedy.

First, let me emphasize that it’s not just Ms. Deschanel, who strives for cute but often achieves insufferable on her new sitcom, “New Girl” (Fox). I haven’t been amused by any sitcoms that hit the air this fall, although millions of Americans seem to tolerate them. “New Girl” and “2 Broke Girls” (CBS) are in the Top 20 in the ratings category that matters most to advertisers, ages 18 to 49. So is “Two and a Half Men” (CBS), an established sitcom that might as well be new because it underwent a radical cast change over the summer. “Whitney,” another aren’t-I-cute gal show starring Whitney Cummings, has been given a full-season extension on NBC, as have the awful “Suburgatory” and “Last Man Standing” on ABC and others.

Yes, people are apparently watching these shows. But I have a hard time believing that many are laughing at them, or at least many in my age bracket, which is the one just after the aforementioned 18-to-49s.

Photo

Jerry Seinfeld in an episode titled "The Contest" from the fourth season of his sitcom, "Seinfeld."Credit
Sony Pictures Television

I don’t think my disenchantment is a result of graduating to cranky-old-man status. Heck, I was cranky when I was 25, but I still laughed at “M*A*S*H.” No, it’s definitely the End of Comedy. As with Francis Fukuyama’s much-discussed essay “The End of History,” that doesn’t mean there will be no more small-screen humor. It means that television comedy has ceased evolving.

Certainly no series introduced this fall is breaking new ground. Ms. Deschanel’s show — her character moves in with three guys — is a role-reversed “Three’s Company.” “Up All Night” on NBC, with Christina Applegate and Will Arnett, is working new-parent territory explored 60 years ago by “I Love Lucy.” On “Last Man Standing,” Tim Allen is basically doing a Tim Allen impersonation, trying (unsuccessfully) to conjure the magic of his earlier show, “Home Improvement.”

So it’s not that the new series are going places I’m not willing to follow; it’s that they are going places I’ve already been. After an exhaustive study that consisted of watching several new shows and several old ones, I have concluded that all television jokes going back to those first flickering black-and-white images fall into one of five categories. All those categories have been worked so heavily and so well in the past that comedic time has shrunk and comedic tone has degenerated; shows don’t want to risk building their humor slowly or subtly because they’re afraid audiences have already seen too many dumb-dad or balky-toaster bits and will grow impatient.

1. GUESS WHAT? WE HAVE GENITALS Nothing has been more prevalent on new sitcoms this fall than the organs and bodily functions centered just below the navel but above the knees. Ashton Kutcher made sure he made an impression in his “Two and a Half Men” debut by strolling around naked. Kat Dennings tossed off a “vagina” a minute into the first episode of “2 Broke Girls.” A few weeks ago on “New Girl,” Ms. Deschanel’s character accidentally saw one of her roommates naked and couldn’t shut up about it, or It.

Much of this barrage, though, has felt ham-handed, a clumsy celebration of the fact that the censors who used to keep words like “vagina” and “penis” out of prime time have apparently all died. We can say this, therefore we’re going to say it over and over.

But there have always been genital references on television; it’s just that the people making them in the past (besides needing to please those censors) knew that subtle is funnier than brazen.

Consider “The Contest,” the legendary 1992 episode of “Seinfeld.” It involves a bet between the four main characters as to who can go the longest without masturbating. It is startling in its fearlessness, even today. And, most notably, it never uses the word “masturbation.” That’s part of its brilliance.

Contrast that with the naked-roommate episode of “New Girl.” It is all about the character Nick’s penis, which Ms. Deschanel’s character, Jess, has accidentally seen. The word “penis” is spoken (or, in one case, sung) nine times, and that’s not including a batch of near-penises as Jess struggles to say the word. (Eventually, of course, she does.) It’s all done with an episode-long smirk, the very smirk I affected back in junior high when using what I thought would be an attention-getting word. And I might have found “New Girl” funny when I was in junior high. The thing is, I’ve graduated. Sorry, New Girl; no laugh for you.

2. TECHNOLOGY EXISTS TO MAKE US LOOK STUPID Man-against-machine humor goes back a long way, perhaps most famously to two women: Lucy and Ethel trying to keep up with that candy conveyor belt in 1952. When this genre was young, you could make a satisfying extended joke out of characters’ inability to master technology. Take Episode 4, Season 1, of “Gilligan’s Island.”

A plane is due to pass over, and the castaways might be able to contact it if the Skipper, a sleepwalker, can doze off and relive a moment during World War II when he turned a radio into a transmitter. The episode is spent tranquilizing and hypnotizing him, building to a classic Gilligan sight gag. After everyone else goes off to bed frustrated, Gilligan brings the transmitter to life just by pounding on it. He talks briefly to the pilot, then fetches the Skipper.

“But how could you have fixed the radio?” the Skipper asks, to which Gilligan responds, “Oh, it was easy; all I did was hit it like this,” and he pounds on it again. The radio’s guts fall to the ground. Another potential rescue foiled.

These days, bad cellphone reception and frozen computers are so common that any joke in this sphere just seems tired. But shows keep revisiting the subject anyway. “Last Man Standing,” Mr. Allen’s retro-man new sitcom, likes to do this, but only for easy quickies. In the premiere, his wife mentions their daughter’s vlog. “Vlog?” Mr. Allen’s character says. “Is that slang for something bad?” And then he turns the word into — wait for it — a penis joke.

3. PARENTS+KIDS=WAR Sitcoms built around a family may have a veneer of love, but that is covering a warmongering heart. This war, though, is rarely fought with guns; it’s psychological.

And it’s as old as “Cleaning Up Beaver,” Episode 21 of Season 1 of “Leave It to Beaver,” first broadcast in 1958.

June is lamenting the Beaver’s messiness. Ward suggests applying psychological pressure by praising the cleanliness of the Beav’s older brother, Wally. “It works down at the office,” he tells June. “Every time we have a sales meeting, we praise the fellows who have gone over their quotas. Then the guys who have been kind of dragging along get the idea.”

The entire episode is built on this chess match, the Beaver reacting to his enemy’s manipulation in ways that turn the parents against each other. Classic divide-and-conquer, expertly unspooled over 25 minutes 48 seconds.

Move ahead to the October premiere of “Reed Between the Lines,” a plodding family sitcom on BET. Carla, the mother and actually a psychologist, is trying the same sort of mind games on her daughter Kaci, hoping to trick her into revealing details about a boy she likes. The kid lets the mom go on for 15 seconds, then says, “You’re using reverse psychology on me like I’m one of your patients.”

What in 1958 occupied 25 minutes is now condensed into 15 seconds. Television’s parent-child war, once full of intricate battle plans and troop movements, has degenerated into a snarky guerrilla contest made of quick, largely mirthless strikes.

4: EEK, A BABY Before you even ask, no, babies do not fit under Category 3 because they are not fully formed people in a television sense; they can’t memorize lines or demand their own trailers. But they’ve been a constant source of humor since television was invented. The latest befuddled new parents are Chris and Reagan on “Up All Night.”

The Nov. 16 episode opens just as Chris has finished feeding the child. His shirt has a blob of baby food on it, and he’s angry. “Oh, honey, she’s just a baby,” Reagan says. Chris barks: “Yeah, that’s what she wants you to think. Why don’t you ask her what happened with the sweet potatoes?” And he storms out. Funny? Maybe a little.

Back in 1996, the “Third Rock From the Sun” episode “My Mother the Alien” also had a spitting baby, one that was being fed by Tommy and Harry, the space alien brothers. But this scene didn’t give up so easily. The baby spits at them awhile, then the camera angle shifts, so that the camera becomes the baby’s point of view. The baby spits some more, until finally Harry takes a mouthful of something and spits it on the baby — that is, onto the camera lens. Funny? Very. The difference? Taking the time to find the unexpected perspective, something the new comedies rarely do.

5: CLODS IN THE WORKPLACE This category has assorted subsections: The Boss Is the Dumbest Person in the Building, for instance. Since this is a season of shows created by and about women, we’ll here look at one in particular: Men Don’t Get It.

In the “2 Broke Girls” pilot, just before she says “vagina,” Ms. Dennings, who plays a diner waitress, smacks down the cook by saying: “Hey, when you get a second? Stop looking at my boobs.” Sure, it was a throwaway line, and even a little amusing, but the shorthand it represents is dismaying somehow. The male-female workplace dynamic has been so thoroughly strip-mined that all you have to do these days is make a passing reference to it.

Things were different in 1972, when “The Mary Tyler Moore Show” began Season 3 with Mary’s discovery that the man who held her job before her was paid substantially more than she gets.

In a wonderfully drawn scene, she haltingly tries to confront her boss (Ed Asner’s Lou Grant) about this, stuttering, stammering, and then finally getting it out: “I would like to know why the last associate producer before me made $50 a week more than I do.” Lou barely registers the question. “Oh, because he was a man,” he says matter-of-factly.

And the scene goes on, saying a lot by contrasting his cluelessness with her budding indignation. Because of the strip-mining, today’s series don’t have that luxury of time. They have only the quick jab, and the payoff isn’t nearly as rich.

If sitcoms are merely rehashing the same five categories of jokes, they’re also just shuffling the same handful of situations. Family with precocious kids. Workplace full of kooks. The young and hip being young and hip. You might think that the been-there-done-that thing isn’t an issue for viewers in a younger demographic, but thanks to Nick at Nite and such, it is; they too have seen all those shows we cranky geezers grew up on.

And so here at the End of Comedy, there’s nothing left to do but embrace a recycling ethic: shuffle the various well-established pieces around and hope someone chuckles. Have the “Odd Couple” guys baby-sit the “Modern Family” youngsters. Put Archie Bunker on a plane next to Corporal Klinger. No new shows need to be filmed; just open up the archives and let people create their own. Mash-Up TV. Sounds like the future.

A version of this article appears in print on November 27, 2011, on page AR1 of the New York edition with the headline: Naked Truth: New Sitcoms Are Reruns. Order Reprints|Today's Paper|Subscribe